Q. Centripetal force is responsible to -
1) keep the body moving along the circular path
2) fly the object along a straight line
3) the independent motion of the object in space
4) None of the above
Q. Which among the following is a positively charged particle emitted by a radioactive element?
1) Beta ray
2) Alpha ray
3) Cathode ray
4) None of the above
Q. A goalkeeper in a game of football pulls his hands backward after holding the ball shot at the goal. This enables the goalkeeper to -
1) exert a large force on the ball
2) increase the force exerted by the ball on the hands
3) decrease the rate of change of momentum
4) None of the above
Q. Ball bearings are used to convert static friction into -
1) drag
2) sliding friction
3) rolling friction
4) None of the above
Q. Which of the following photoelectric devices is most suitable for digital applications?
1) Photovoltaic cell
2) Photoemitter
3) Photodiode
4) None of the above
Q. The shrillness of sound is determined by -
1) amplitude of sound
2) wavelength of sound
3) velocity of sound
4) None of the above
Q. A large number of thin strips of black paint are made on the surface of a convex lens of focal length 20 cm to catch the image of a white horse. The image will be -
1) a zebra of black stripes
2) a horse with black stripes
3) a horse of less brightness
4) None of the above
Q. Which of the following statements is/are correct about 'quasicrystal'?
1. In a 'quasicrystal' atoms are arranged in a repeating pattern.
2. 'Quasicrystals' are used in manufacturing non-stick frying pans, needles for acupuncture and surgery, dental instruments, and razor blades.
1) Only 1 is correct
2) Only 2 is correct
3) Both 1 and 2 are correct
4) Neither 1 nor 2 is correct
Q. When will a magnet lose its magnetism?
1) If it is cooled very much, say below absolute zero
2) If it is placed without the keepers
3) If it is heated strongly or hammered strongly
4) Once a magnet always a magnet
Q. Energy conversions taking place in a microphone are -
1) Sound to mechanical to electrical
2) Electrical to mechanical to sound
3) Sound to mechanical
4) Mechanical to sound